1. Field
The following description relates to a filter using bulk acoustic wave resonators (BAWRs) and a filter circuit using the BAWRs.
2. Description of Related Art
An analog radio frequency (RF) region is a region ranging from an end of an antenna to an end of a mixer in a communication of a mobile communication terminal.
To use frequencies of various bands in an analog RF region, a number of passive components such as an antenna, a filter, a duplexer, and a matching circuit may proportionally increase. An area used by the passive components and a requirement for a characteristic enhancement may also proportionally increase.
Accordingly, a high performance filter is achieved using bulk acoustic wave resonators (BAWRs) having an excellent resonator characteristic.
In general, a filter using the BAWRs uses a method of arranging the BAWRs in a ladder type or a lattice type using only the BAWRs, or a method of additionally connecting an inductor to a portion of the BAWRs.
When increasing a number of ends to achieve a high performance using the aforementioned structure, there is a difficulty in achieving a desired filter performance in a transmission band due to resonance frequency and anti-resonance frequency characteristics of the BAWRs limited in a process and a twisting of matching occurring between the respective ends.